The invention relates to a method and a device for injecting liquid in a screw compressor comprising a screw cam rotor and a screw thread rotor enclosing the screw cam rotor which rotors are rotatably journalled in a housing for rotation around mutually sideways displaced rotation axes and thereby form chambers for a working medium between their screw cam means and screw thread means which chambers during rotation move from a low pressure end to a high pressure end of the rotors while decreasing their volumes.
In such screw compressors of which suggestions are shown e.g. in Swedish patent specification No. 85,331 and U.S. Pat. specification Nos. 1,892,217 and 2,553,548 practical operation at high pressures and simultaneous cooling through liquid injection has not yet been realized.